Abstract: A continuously variable transmission (CVT) including a hydraulically-controllable variator is described. A method for controlling the CVT includes detecting a transient event causing a commanded change in a speed ratio of the variator and disabling feedback control of hydraulic pressure to the variator during the transient event. A target pressure that achieves the commanded change in the speed ratio of the variator is determined, and a pressure trajectory is determined based upon the target pressure. A feed-forward control of the hydraulic pressure to the variator is executed in response to the pressure trajectory during the transient event.

Abstract: A method and apparatus for controlling a continuously variable transmission (CVT) of a powertrain system includes determining a target clamping pressure and an actual clamping pressure, and determining a proportional correction term and an integral correction term based upon the target clamping pressure and the actual clamping pressure. An adapt correction term is determined based upon the target clamping pressure and a temperature of the CVT. A commanded clamping pressure for controlling the CVT is determined based upon the proportional correction term, the integral correction term and the adapt correction term. A pressure command is employed to drive an actuator of a moveable sheave of a pulley of a variator of the CVT based upon the commanded clamping pressure.

Abstract: A continuously variable transmission (CVT) for use with a torque generating mechanism includes an input member connectable to the torque generating mechanism, an output member, a variator assembly, and a controller. The controller is programmed to control a change-of-mind shift of the CVT requesting a transition from an initially-requested shift to a next-requested shift before completion of the initially-requested shift. Additionally, the controller is programmed to execute a method by detecting the change-of-mind shift, determining an acceleration profile of the input member for the change-of-mind shift using a calibration map indexed by a starting and target ratio of the variator assembly, and calculating a required ratio of the input and output pulleys using the acceleration profile. The controller then commands a clamping pressure of the variator assembly to thereby achieve the calculated required ratio. A vehicle includes an engine and the CVT noted above.

Abstract: A powertrain includes a torque generative device and a torque converter having an impeller, a turbine and a torque converter clutch. A method to control torque converter slip includes a feedforward component and a feedback component. The feedforward component includes monitoring a reference slip, and actual slip, and a turbine speed of the torque converter, determining a desired turbine torque based upon the reference slip and the turbine speed, determining an actual turbine torque based upon the actual slip and the turbine speed, determining a feedforward torque converter clutch pressure command based upon the desired turbine torque, the actual turbine torque, a torque generative device torque, and a TCC gain, and determining feedforward torque converter clutch pressure command. The feedback component modifies the feedforward command pressure based on proportional plus integral plus differential (PID) slip feedback terms.

Abstract: A method of controlling a variator that requires clamping pressure between a first component and a second component to transfer torque therebetween, such as a continuously variable transmission, includes calculating a theoretical clamping pressure, and multiplying the theoretical clamping pressure by a multiplier to define a commanded clamping pressure. The multiplier includes a value that is variable between a minimum multiplier value and a maximum multiplier value. The value of the multiplier is based on current operating conditions of the variator. The commanded clamping pressure is applied to the first component and the second component to generate friction and transfer torque between the first component and the second component.

Abstract: A powertrain includes a torque generative device and a torque converter having an impeller, a turbine and a torque converter clutch. A method to control torque converter slip includes a feedforward component and a feedback component. The feedforward component includes monitoring a reference slip, and actual slip, and a turbine speed of the torque converter, determining a desired turbine torque based upon the reference slip and the turbine speed, determining an actual turbine torque based upon the actual slip and the turbine speed, determining a feedforward torque converter clutch pressure command based upon the desired turbine torque, the actual turbine torque, a torque generative device torque, and a TCC gain, and determining feedforward torque converter clutch pressure command. The feedback component modifies the feedforward command pressure based on proportional plus integral plus differential (PID) slip feedback terms.

Abstract: A powertrain system including an internal combustion engine rotatably coupled to a variator of a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining an actual speed ratio, a desired speed ratio and a commanded speed ratio. A total speed ratio change rate is determined based upon the actual speed ratio, the desired speed ratio and the commanded speed ratio, and a commanded speed ratio trajectory is determined based upon the desired speed ratio and the commanded speed ratio. A ratio change coefficient and a force ratio factor are determined based upon the commanded speed ratio trajectory, and a shift force is determined based upon the total speed ratio change rate and the ratio change coefficient. A primary pulley force and a secondary pulley force for the CVT are controlled based upon the shift force and the force ratio factor.

Abstract: A continuously variable transmission (CVT) for use with a torque generating mechanism includes an input member connectable to the torque generating mechanism, an output member, a variator assembly, and a controller. The controller is programmed to control a change-of-mind shift of the CVT requesting a transition from an initially-requested shift to a next-requested shift before completion of the initially-requested shift. Additionally, the controller is programmed to execute a method by detecting the change-of-mind shift, determining an acceleration profile of the input member for the change-of-mind shift using a calibration map indexed by a starting and target ratio of the variator assembly, and calculating a required ratio of the input and output pulleys using the acceleration profile. The controller then commands a clamping pressure of the variator assembly to thereby achieve the calculated required ratio. A vehicle includes an engine and the CVT noted above.

Abstract: A powertrain system including an internal combustion engine rotatably coupled to a variator of a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining a first speed ratio change rate based upon a desired speed ratio and a commanded speed ratio, and determining a commanded speed ratio trajectory based upon the first speed ratio change rate, an actual speed ratio and a commanded speed ratio. A ratio change coefficient and a force ratio factor are determined based upon the commanded speed ratio trajectory. A shift force is determined based upon the ratio change coefficient and a total speed ratio change rate. A primary pulley pressure and a secondary pulley pressure for the CVT are controlled based upon the shift force and the force ratio factor.

Abstract: A continuously variable transmission (CVT) including a hydraulically-controllable variator is described. A method for controlling the CVT includes detecting a transient event causing a commanded change in a speed ratio of the variator and disabling feedback control of hydraulic pressure to the variator during the transient event. A target pressure that achieves the commanded change in the speed ratio of the variator is determined, and a pressure trajectory is determined based upon the target pressure. A feed-forward control of the hydraulic pressure to the variator is executed in response to the pressure trajectory during the transient event.

Abstract: A powertrain system including an internal combustion engine rotatably coupled to a variator of a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining an actual speed ratio, a desired speed ratio and a commanded speed ratio. A total speed ratio change rate is determined based upon the actual speed ratio, the desired speed ratio and the commanded speed ratio, and a commanded speed ratio trajectory is determined based upon the desired speed ratio and the commanded speed ratio. A ratio change coefficient and a force ratio factor are determined based upon the commanded speed ratio trajectory, and a shift force is determined based upon the total speed ratio change rate and the ratio change coefficient. A primary pulley force and a secondary pulley force for the CVT are controlled based upon the shift force and the force ratio factor.

Abstract: A powertrain system including a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining a target clamping pressure and an actual clamping pressure, and determining a proportional correction term and an integral correction term based upon the target clamping pressure and the actual clamping pressure. An adapt correction term is determined based upon the target clamping pressure and a temperature of the CVT. A commanded clamping pressure for controlling the CVT is determined based upon the proportional correction term, the integral correction term and the adapt correction term. A pressure command is employed to drive an actuator of a moveable sheave of a pulley of a variator of the CVT based upon the commanded clamping pressure.

Abstract: A powertrain system including an internal combustion engine rotatably coupled to a variator of a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining a first speed ratio change rate based upon a desired speed ratio and a commanded speed ratio, and determining a commanded speed ratio trajectory based upon the first speed ratio change rate, an actual speed ratio and a commanded speed ratio. A ratio change coefficient and a force ratio factor are determined based upon the commanded speed ratio trajectory. A shift force is determined based upon the ratio change coefficient and a total speed ratio change rate. A primary pulley pressure and a secondary pulley pressure for the CVT are controlled based upon the shift force and the force ratio factor.

Abstract: A powertrain system including an internal combustion engine rotatably coupled to a variator of a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining a desired variator speed ratio in response to a command to increase output power from the powertrain system and executing a step-down shift in the CVT based upon the desired variator speed ratio, the step-down shift. The step-down shift includes determining a preferred CVT input acceleration profile based upon the desired variator speed ratio, a present variator speed ratio, and a preferred shift time and synchronizing the preferred CVT input acceleration profile with engine torque. A change rate for the variator speed ratio is based upon the preferred CVT input acceleration profile, and the CVT is controlled in response to the change rate for the variator speed ratio and the desired variator speed ratio.

Abstract: A powertrain system including an internal combustion engine rotatably coupled to a variator of a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining a desired variator speed ratio in response to a change in an operator input and executing a step-upshift in the CVT based upon the desired variator speed ratio. The step-upshift includes determining a preferred CVT input deceleration profile based upon the desired variator speed ratio, a present variator speed ratio, and a preferred shift time and synchronizing the preferred CVT input deceleration profile with a command to reduce engine torque. A change rate for the variator speed ratio is based upon the preferred CVT input deceleration profile, and the CVT is controlled in response to the change rate for the variator speed ratio and the desired variator speed ratio.

Abstract: A continuously variable transmission (CVT) includes input and output members, a primary variator pulley, and a secondary variator pulley. The respective variator pulleys are responsive to primary and secondary pressures. Speed sensors measure a respective rotational speed of each variator pulley. A controller executes a method by receiving the measured rotational speeds, calculating a current speed ratio of the CVT above a threshold CVT speed ratio using the rotational speeds, comparing the calculated current speed ratio to calibrated threshold ratios during a sudden stop event of the vehicle, and selectively executing a CVT control action after the calculated current speed ratio drops below the threshold CVT speed ratio during the sudden stop event. The control action depends on which of the threshold ratios is exceeded by the calculated current speed ratio after the calculated current speed ratio drops below the threshold CVT speed ratio, and on the measured rotational speeds.

Abstract: A continuously variable transmission (CVT) includes input and output members, a primary variator pulley, and a secondary variator pulley. The respective variator pulleys are responsive to primary and secondary pressures. Speed sensors measure a respective rotational speed of each variator pulley. A controller executes a method by receiving the measured rotational speeds, calculating a current speed ratio of the CVT above a threshold CVT speed ratio using the rotational speeds, comparing the calculated current speed ratio to calibrated threshold ratios during a sudden stop event of the vehicle, and selectively executing a CVT control action after the calculated current speed ratio drops below the threshold CVT speed ratio during the sudden stop event. The control action depends on which of the threshold ratios is exceeded by the calculated current speed ratio after the calculated current speed ratio drops below the threshold CVT speed ratio, and on the measured rotational speeds.

Abstract: A method of controlling a variator that requires clamping pressure between a first component and a second component to transfer torque therebetween, such as a continuously variable transmission, includes calculating a theoretical clamping pressure, and multiplying the theoretical clamping pressure by a multiplier to define a commanded clamping pressure. The multiplier includes a value that is variable between a minimum multiplier value and a maximum multiplier value. The value of the multiplier is based on current operating conditions of the variator. The commanded clamping pressure is applied to the first component and the second component to generate friction and transfer torque between the first component and the second component.

Abstract: A vehicle includes an engine, drive wheels, a continuously variable transmission (CVT), and a controller. The CVT includes an input member connected to the engine, an output member delivering output torque to the wheels, and a variator assembly connecting the input and output members. The controller determines, via a method, an input and output speed of the variator assembly, converts the output speed to an equivalent input speed using a calibrated variator speed ratio, and calculates a gross slip of the variator assembly using the input and equivalent input speeds. A gross slip flag is set only when the gross slip exceeds a calibrated slip value for a predetermined duration. A CVT assembly includes the controller, input and output members, and variator assembly. The variator assembly may include drive and driven pulleys, a drive mechanism connecting the pulleys, and an actuator applying a clamping force to one of the pulleys.

Abstract: A vehicle includes an engine, drive wheels, a continuously variable transmission (CVT), and a controller. The CVT includes an input member connected to the engine, an output member delivering output torque to the wheels, and a variator assembly connecting the input and output members. The controller determines, via a method, an input and output speed of the variator assembly, converts the output speed to an equivalent input speed using a calibrated variator speed ratio, and calculates a gross slip of the variator assembly using the input and equivalent input speeds. A gross slip flag is set only when the gross slip exceeds a calibrated slip value for a predetermined duration. A CVT assembly includes the controller, input and output members, and variator assembly. The variator assembly may include drive and driven pulleys, a drive mechanism connecting the pulleys, and an actuator applying a clamping force to one of the pulleys.